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>Video for Linux Two API Specification: Revision 0.24</TH
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><H1
><A
NAME="VIDIOC-ENUM-FMT"
></A
>ioctl VIDIOC_ENUM_FMT</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN8371"
></A
><H2
>Name</H2
>VIDIOC_ENUM_FMT&nbsp;--&nbsp;Enumerate image formats</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN8374"
></A
><H2
>Synopsis</H2
><DIV
CLASS="FUNCSYNOPSIS"
><P
></P
><A
NAME="AEN8375"
></A
><P
><CODE
><CODE
CLASS="FUNCDEF"
>int ioctl</CODE
>(int fd, int request, struct v4l2_fmtdesc
*argp);</CODE
></P
><P
></P
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN8385"
></A
><H2
>Arguments</H2
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><CODE
CLASS="PARAMETER"
>fd</CODE
></DT
><DD
><P
>File descriptor returned by <A
HREF="r14090.htm"
><CODE
CLASS="FUNCTION"
>open()</CODE
></A
>.</P
></DD
><DT
><CODE
CLASS="PARAMETER"
>request</CODE
></DT
><DD
><P
>VIDIOC_ENUM_FMT</P
></DD
><DT
><CODE
CLASS="PARAMETER"
>argp</CODE
></DT
><DD
><P
></P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN8405"
></A
><H2
>Description</H2
><P
>To enumerate image formats applications initialize the
<CODE
CLASS="STRUCTFIELD"
>type</CODE
> and <CODE
CLASS="STRUCTFIELD"
>index</CODE
>
field of struct&nbsp;<A
HREF="r8367.htm#V4L2-FMTDESC"
>v4l2_fmtdesc</A
> and call the
<CODE
CLASS="CONSTANT"
>VIDIOC_ENUM_FMT</CODE
> ioctl with a pointer to this
structure. Drivers fill the rest of the structure or return an
<SPAN
CLASS="ERRORCODE"
>EINVAL</SPAN
> error code. All formats are enumerable by beginning at index zero and
incrementing by one until <SPAN
CLASS="ERRORCODE"
>EINVAL</SPAN
> is
returned.</P
><DIV
CLASS="TABLE"
><A
NAME="V4L2-FMTDESC"
></A
><P
><B
>Table 1. struct <CODE
CLASS="STRUCTNAME"
>v4l2_fmtdesc</CODE
></B
></P
><TABLE
BORDER="0"
FRAME="void"
WIDTH="100%"
CLASS="CALSTABLE"
><COL
WIDTH="25%"
TITLE="C1"><COL
WIDTH="25%"
TITLE="C2"><COL
WIDTH="50%"
TITLE="C3"><TBODY
VALIGN="TOP"
><TR
><TD
>__u32</TD
><TD
><CODE
CLASS="STRUCTFIELD"
>index</CODE
></TD
><TD
>Number of the format in the enumeration, set by
the application. This is in no way related to the <CODE
CLASS="STRUCTFIELD"
>pixelformat</CODE
> field.</TD
></TR
><TR
><TD
>enum&nbsp;<A
HREF="x5953.htm#V4L2-BUF-TYPE"
>v4l2_buf_type</A
></TD
><TD
><CODE
CLASS="STRUCTFIELD"
>type</CODE
></TD
><TD
>Type of the data stream, set by the application.
Only these types are valid here:
<CODE
CLASS="CONSTANT"
>V4L2_BUF_TYPE_VIDEO_CAPTURE</CODE
>,
<CODE
CLASS="CONSTANT"
>V4L2_BUF_TYPE_VIDEO_OUTPUT</CODE
>,
<CODE
CLASS="CONSTANT"
>V4L2_BUF_TYPE_VIDEO_OVERLAY</CODE
>, and custom (driver
defined) types with code <CODE
CLASS="CONSTANT"
>V4L2_BUF_TYPE_PRIVATE</CODE
>
and higher.</TD
></TR
><TR
><TD
>__u32</TD
><TD
><CODE
CLASS="STRUCTFIELD"
>flags</CODE
></TD
><TD
>See <A
HREF="r8367.htm#FMTDESC-FLAGS"
>Table 2</A
></TD
></TR
><TR
><TD
>__u8</TD
><TD
><CODE
CLASS="STRUCTFIELD"
>description</CODE
>[32]</TD
><TD
>Description of the format, a NUL-terminated ASCII
string. This information is intended for the user, for example: "YUV
4:2:2".</TD
></TR
><TR
><TD
>__u32</TD
><TD
><CODE
CLASS="STRUCTFIELD"
>pixelformat</CODE
></TD
><TD
>The image format identifier. This is a
four character code as computed by the v4l2_fourcc()
macro:</TD
></TR
><TR
><TD
COLSPAN="3"
><P
><PRE
CLASS="PROGRAMLISTING"
>#define v4l2_fourcc(a,b,c,d) (((__u32)(a)&lt;&lt;0)|((__u32)(b)&lt;&lt;8)|((__u32)(c)&lt;&lt;16)|((__u32)(d)&lt;&lt;24))</PRE
></P
><P
>Several image formats are already
defined by this specification in <A
HREF="c2030.htm"
>Chapter 2</A
>. Note these
codes are not the same as those used in the Windows world.</P
></TD
></TR
><TR
><TD
>__u32</TD
><TD
><CODE
CLASS="STRUCTFIELD"
>reserved</CODE
>[4]</TD
><TD
>Reserved for future extensions. Drivers must set
the array to zero.</TD
></TR
></TBODY
></TABLE
></DIV
><DIV
CLASS="TABLE"
><A
NAME="FMTDESC-FLAGS"
></A
><P
><B
>Table 2. Image Format Description Flags</B
></P
><TABLE
BORDER="0"
FRAME="void"
WIDTH="100%"
CLASS="CALSTABLE"
><COL
WIDTH="38%"
TITLE="C1"><COL
WIDTH="12%"
TITLE="C2"><COL
WIDTH="50%"
TITLE="C3"><TBODY
VALIGN="TOP"
><TR
><TD
><CODE
CLASS="CONSTANT"
>V4L2_FMT_FLAG_COMPRESSED</CODE
></TD
><TD
>0x0001</TD
><TD
>This is a compressed format.</TD
></TR
></TBODY
></TABLE
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN8479"
></A
><H2
>Return Value</H2
><P
>On success <SPAN
CLASS="RETURNVALUE"
>0</SPAN
> is returned, on error <SPAN
CLASS="RETURNVALUE"
>-1</SPAN
> and the <CODE
CLASS="VARNAME"
>errno</CODE
> variable is set appropriately:</P
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><SPAN
CLASS="ERRORCODE"
>EINVAL</SPAN
></DT
><DD
><P
>The struct&nbsp;<A
HREF="r8367.htm#V4L2-FMTDESC"
>v4l2_fmtdesc</A
> <CODE
CLASS="STRUCTFIELD"
>type</CODE
>
is not supported or the <CODE
CLASS="STRUCTFIELD"
>index</CODE
> is out of
bounds.</P
></DD
></DL
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